Fire extinguishing composition and method of making it



July 24, 1962 s. VOINOVICH 3,046,220

Filed Oct. 25, 1957 PERCENT OF MAGNESIUM REMAINING IO% I00% CLAY (Remainder Pitch) Fig! 2 3 4- 5 6 7 8 9 I0 PARTS BY WEIGHT 0F NH 0L INVENTOR.

TO MIXTURE OF FOUR PARTS Sweeney WWW/c" CLAY To ONE PART PITCH BY Fig. 2 mdwfiw HIS ATTORNE Y8 United States Patent 3,M6,ZZO Patented July 24, 1962 3,046,220 FIRE EXTINGUISG COMPGSITION AND METHOD OF MAKING IT Sweeney Voinovich, Bridgeville, Pa, assignor to Mercantile Metals, Inc, Carnegie, Pa, a corporation of Pennsylvania Filed Oct. 25, 1957, Ser. No. 692,396 3 Claims. c1. 2s2 z This application relates to a fire extinguishing composition, more particularly to a fire extinguishing composition for extinguishing fires of burning metals. As is well known, metal fires,'such as those formed by the burning of magnesium, aluminum, lithium, sodium, potassium, thorium, zirconium, hafnium, uranium, etc., not only burn at high temperatures but are extremely diflicult to extinguish by ordinary fire extinguishing techniques. For example, the fires cannot be put out with water since the oxygen in the water combines with the burning metal and increases the intensity of the fire.

I have discovered that such metal fires can be extinguished by covering them with a composition comprising a mixture of ground pitch or bituminous material and an inert, inorganic, substantially non-fusible substance such as clay, shale, sand, etc. which has been ground. Using this composition, a metal fire can be extinguished by covering the burning metal particles with the composition or by mixing the composition with the burning metal particles. The pitch or bitiuminous material, upon coming into contact with the burning metal, melts, absorbs some heat and forms an oxygen-excluding coating over the metal particles. The fire is thus extinguished by depriving the metal of oxygen. The action of the inert, inorganic substance is twofold. First, it increases dilatency of the pitch or bituminous material and serves to keep it on the burning metal. Second, the inert, inorganic material lowers the temperature of the burning particles.

Fire extinguishing compositions of this broad type are known. See, for example, United States Patent No. 2,232,695 to Durston et 21. My fire extinguishing composition, however, has several advantages over the previously known compositions. First, I have found that the proportions of the ingredients of the composition should be kept within certain relatively narrow limits. Second, I have developed an improved process for making the mixtures :whereby the ingredients are agglomerated into particles of suficient size that they may be projected onto a fire manually or mechanically from a distance. Finally, I have discoverd that the effectiveness of the composition may be materially improved by the addition of ammonium chloride in certain rather limited proportions.

In the accompanying drawings:

FIGURE 1 is a graph showing the effectiveness of fire extinguishing compositions having varying proportions of pitch and an inert, inorganic substance, in this case clay; and

FIGURE 2 is a graph showing the elfect of the addition of ammonium chloride in varying amounts to a fire extinguishing composition.

When using the word pitch, throughout the specification and claims, I am using the word pitch in its broad sense as including not only bituminous materials but productsobtained by distillation or refining of fats, oils, wood tars, etc. The essential requirements of the pitch are that it be a hydrocarbon containing no oxygen and have a melting point below the temperature of the fire on which it is to be used, that it be chemically inert to prior to mixing with the other ingredients of the fire extinguishing composition. I have found that a pitch known as mineral rubber meets these requirements.

The other chief constituent of my fire extinguishing composition is an inorganic substance which is inert and substantially non-fusible when applied to the fire. That "is to say, the material does not melt or change when the mixture containing it comes into contact with the fire. Preferably, it should also have a relatively high specific gravity and, therefore, a relatively high heat conductivity and absorption. A large number of substances can meet this requirement, for example, sand, aluminum oxide, iron oxide, pulverized furnace slag oxide, shale, and clay. I have found ground clay to be quite satisfactory.

I have found that the proportions of the two principal ingredients of my composition should be kept within certain relatively narrow limits. Thus, I conducted a series of tests in which given quantities of magnesium turnings were ignited, allowed to burn for a definite period of time, and then covered with compositions having varying proportions of ingredients. After the fire was extinguished by the composition, I removed from the residue all unburned magnesium and weighed it, the amount of unburned magnesium remaining being proportional to the efiectiveness of the composition; i.e., the more unburned magnesium remaining the more effective the composition.

In the tests, I used 10 gram samples of magnesium turnings. I applied a flame for 15 seconds to each sample to start a fire and I allowed each sample to burn for 2 /2 minutes. At the end of 2 /2 minutes, I covered the fire with 28 grams of fire extinguishing composition containing mineral rubber and clay, the ingredients in the composition varying in proportions from test to test. I ran 7 or 8 tests of each proportion and took the average value of the recovered unburned magnesium.

FIGURE 1 of the accompanying drawings is a graph showing the results of these tests. Reviewing FIGURE 1, it will be noted that proportions of the ingredients are critical and that the most efiicient composition is one which is clay, i.e., 4 parts by weight of clay to 1 part of pitch.

While the best results are obtained from a composition which is 4 parts by weight of clay to 1 part by weight of pitch, mixtures containing 72 to 84% of clay by weight are slightly less desirable but still produce eifective results. For many purposes, I can employ mixtures containing from 66% to 87 /2% clay (2 parts by weight of clay to 1 part of pitch to 7 parts by weight of clay to 1 part of pitch, which, as shown in FIGURE 1, extinguished a magnesium fire after 40% of the magnesium had been consumed. The actual proportions used within this latter range are determined by practical considerations, namely, the desirability of extinguishing a fire as promptly as possible, saving as much of the burning metal as possible, and not using on the fire any more extinguishing composition than is required.

I have also discovered that the efiiciency of my fire extinguishing composition can be materially improved by the addition of ground ammonium chloride. The ammonium chloride acts in two ways in improving the composition. First, upon contact with the fire, the ammomum chloride volatilizes, thus absorbing heat, and condenses on the colder unburned portions of the metal forming the fire and renders those portions fire resistant. The ammonium chloride also forms with the burning magnesium, magnesium chloride, which is incombustible.

In order to determine the amount of ammonium chlor- Me to be used in my composition, I conducted a series of tests similar to those which I conducted to determine the proper proportions of pitch and clay, as described above. In these tests, I used the optimum proportions of pitch and clay as determined in the first series of tests, i.e., 4 parts by weight of clay to 1 part of pitch, and then added ammonium chloride in varying amounts to determine the effectiveness of this addition. FIGURE 2 shows the results of these tests. From this figure, it will be seen that the proper proportion of ammonium chloride to the other ingredients in the composition varies within very narrow limits. Thus, the tests showed that, with no ammonium chloride added, approximately 72% of the magnesium which was initially fired and then extinguished was recovered. When /2 part by weight of ammonium chloride was added to 4 parts by weight of clay and 1 part by weight of pitch, the amount of magnesium recovered rose to approximately 78%. This is a decrease of 21.4% in the amount of magnesium burned. When, however, 1 part by weight of ammonium chloride was added, the recovery returned to the same percentage value it had without any ammonium chloride being added. When further amounts of ammonium chloride were used, the efiiciency dropped rapidly below the value obtained from a composition without ammonium chloride. From FIGURE 2, it appears that ammonium chloride in amounts ranging from 0.1 to 0.9 part by weight to 4 parts by weight of clay and 1 part by weight of pitch are effective and that ammonium chloride in the amount of 0.5 part by weight is most effective.

One of the serious defects of prior fire extinguishing compositions, such, for example, as that shown in the Durston et al. Patent No. 2,232,695, has been the difiiculty of placing the material on the fire. The compositions have been chiefly in powder form, with the result that they cannot be thrown, manually or mechanically, any appreciable distance, particularly if there is any wind or other air current at the fire. Whenever such material is thrown at a fire, any current of air will pick up the powdered material and carry it away from the fire. The result is that the material can be effectively applied only by manually shoveling the material on the fire. This requires that a person approach dangerously close to a fire.

I have developed a process for preparing my composition which produces the composition in agglomerated paritcles of sufficient size that they can be thrown mechanically or manually over an appreciable distance and with satisfactory accuracy. Each of the agglomerated composition particles contains all of the ingredients and in the proper proportions so that a mass of compositions when thrown on a fire is effective for extinguishing the fire.

In the process which I have devised for preparing my composition, I start with pitch which has been ground to a size which preferably will pass through a 20 mesh screen and add a solvent to the pitch to soften, swell, or dissolve it, and disperse the solvent through the pitch. The procedure which I have found most effective consists in adding a solvent to the inert, inorganic material and wetting the material with the solvent to disperse the solvent throughout the inorganic material. The inert, inorganic material is preferably ground to a size which will pass through a mesh screen. I have found that, when the composition is composed of mineral rubber pitch and clay, toluol is an effective solvent when added in the amount of 5% of the weight of the dry materials. I then add the pitch and mix the combined materials in a Sigma mixer. I continue the mixing step until the material agglomerates into particles of desired size.

The mixing of the ingredients with agglomeration into particles should continue until the particles are of suitable size. The minimum size of the particles is determined by the requirement that they maintain a good trajectory when thrown. Therefore, they should have sutficient size that they cannot be wind-borne. That is, they should be bigger than dust particles, which are generally considered to be 100 mesh or smaller. The maximum size of the particles is determined by the fact that the material is thrown onto a fire where the pitch melts and forms over the burning metal an oxygen-excluding covering or cap. Therefore, the particles should not be so large that they will roll off the burning metal before the pitch in the particles has melted.

Forming my fire extinguishing composition into agglomerated particles has several advantages over extinguishing compositions heretofore known, in addition to throwability. The composition may be stored for long periods of time without caking and without separation of the different ingredients of the composition. Likewise, the material can be transported without separation of the ingredients. Of particular importance is the fact that all of the ingredients making up the composition are in each particle and in the proper proportions. Therefore, if a mass of my composition is thrown at a fire, the mass will have within it all the required ingredients in the proper proportions. The agglomeration of the particles also provides a material having a uniform flow so that it can be readily used in mechanical apparatus for projecting the composition at a fire.

My composition can also be used for the storage of metals subject to pyrophoricity, such as plutonium, thorium, uranium, zirconium, etc. As is known, such metals have a tendency to ignite spontaneously, particularly if they are in the form of fine particules. Such metals can be stored in containers in which they are covered or surrounded by a layer of my fire extinglishing composition. If there should be spontaneous ignition of the metal, my composition will either extinguish the fire or restrict it by excluding oxygen from the burning metal.

While I have described certain presently preferred embodiments of my inventions, it is to be understood that they may be otherwise variously embodied within the scope of the appended claims.

I claim:

1. A fire extinguishing composition consisting essentially of ground pitch, a ground, inert, inorganic, nonfusible material, and ground ammonium chloride in the proportions ranging from approximately 2 parts inorganic material to 1 part pitch by weight to 7 parts inorganic material to 1 part pitch by weight, the ammonium chloride being in proportions ranging from 0.1 part to 0.9 part by Weight to the parts by weight of the other ingredients taken singly.

2. A fire extinguishing composition consisting essen tially of ground pitch, a ground, inert, inorganic, nonfusible material, and ammonium chloride in the proportions by weight of approximately 4 parts of inorganic material to 1 part pitch, the ammonium chloride varying in proportion by weight to the parts by weight of the other ingredients taken singly from 0.1 part to 0.9 part.

3. A fire extinguishing composition consisting essentially of ground pitch, powdered clay, and ground ammonium chloride in the proportions by weight of approximately 4 parts of clay, 1 part pitch, and /2 part ammonium chloride.

4. A fire extinguishing composition consisting essentially of ground pitch, a powdered, inert, inorganic, nonfusible material, and ground ammonium chloride in the proportions ranging from approximately 2 parts inorganic material to 1 part pitch by weight to 7 parts inorganic material to 1 part pitch by weight, the ammonium chloride being in proportions ranging from 0.1 part to 0.9 part by weight to the parts by weight of the other ingredients taken singly, the composition being agglomerated in particles at least as large as one hundred mesh.

5. A fire extinguishing composition consisting essentially of ground pitch, a ground, inert, inorganic, nonfusible material, and ammonium chloride in the proportions by weight of approximately 4 parts of inorganic material to 1 part pitch, the ammonium chloride varying in proportion by weight to the parts by weight of the other ingredients taken singly from 0.1 to 0.9 part, the composition being agglomerated in particles at least as large as one hundred mesh.

6. A fire extinguishing composition consisting essentially of ground pitch, powdered clay, and powdered ammonium chloride in the proportions by weight of approximately 4 parts of clay, 1 part pitch, and /2 part ammonium chloride, the composition being agglomerated in particles at least as large as one hundred mesh.

7. A process for preparing a fire extinguishing composition comprising solid particles each containing ground pitch and ground, inert, inorganic non-fusible material in the proportions ranging from approximately 2 parts inorganic material to 1 part pitch by weight to 7 parts inorganic material to 1 part pitch by Weight which comprises adding to the inorganic material a solvent for the pitch, dispersing the solvent in the inorganic material, adding the pitch in ground form and mixing the pitch and inorganic material until the mixture agglomerates into particles of the desired size.

8. A process for preparing a fire extinguishing composition comprising ground-mineral rubber pitch, powdered clay, and ground ammonium chloride in the proportions ranging from approximately 2 parts inorganic material to 1 part pitch by weight to 7 parts inorganic material to 1 part pitch by weight, the ammonium chloride being in proportions ranging from 0.1 part to 0.9

part by weight to the parts by weight of the other in-- gredients taken singly which comprises adding toluol to the clay and ammonium chloride in an amount approximately 5% by weight of the ingredients of the composition dispersing the solvent in the inorganic material, adding the pitch to the clay and ammonium chloride and mixing the materials together until the mixture agglomerates into particles of the desired size.

References Cited in the tile of this patent UNITED STATES PATENTS Hinckley July 25, Klugh Apr. 21, Durston et al. Feb. 25, Fahey et al. Sept. 1, Miller Apr. 20, Fasold et al Sept. 25, Sargent et al Oct. 30, Larsen May 20, Christensen Apr. 2, Fair Sept. 10, McCutchan Mar, 31, Dickenson May 5, Goodwin July 14, Pickell Oct. 20,

FOREIGN PATENTS Great Britain Sept. 8,

Australia July 31,

OTHER REFERENCES Gregory: Uses and Applications of Chemicals and Related Materials, Reinhold Publ. Corp, New York, vol. H (1944), page 17. 

1. A FIRE EXTINGUISHING COMPOSITION CONSISTING ESSENTIALLY OF GROUND PITCH, A GROUND, INERT, INORGANIC, NONFUSIBLE MATERIAL, AND GROUND AMMONIUM CHLORIDE IN THE PROPRTIONS RANGING FROM APPROXIMATELY 2 PARTS INORGANIC MATERIAL TO 1 PART PITCH BY WEIGHT TO 7 PARTS INORGANIC MATERIAL TO 1 PART PITCH BY WEIGHT, THE AMMONIUM CHLORIDE BEING IN PROPOTIONS RANGING FROM 0.1 PART TO 0.9 PART BY WEIGHT TO THE PARTS BY WEIGHT OF THE OTHER INGREDIENTS TAKEN SINGLY. 